Decolorization and demineralization are important steps in refining sugar solutions. Traditionally, sugar solutions have been decolorized and demineralized in a three-step process. The first step involves decolorizing the sugar solution with carbon adsorbents such as activated carbon. The sugar solution is then demineralized by removing cationic and anionic impurities in the second and third steps, respectively. The second step is carried out with a cation exchange resin, and the third step is carried out with an anion exchange resin.
Unfortunately, using activated carbon to decolorize sugar solutions has some drawbacks. One drawback is that activated carbon presents serious handling problems. Since activated carbon particles are very fine, they create clouds of dust when being transferred. This poses a health concern for workers who come into contact with the clouds. Moreover, the particles are very abrasive. Consequently, they have a tendency to wear down equipment relatively quickly.
As a result of the problems associated with using activated carbon, efforts have been made to find an adsorbent having an adsorptive capacity similar to that of activated carbon, but without its drawbacks. One such effort is described in U.S. Pat. No. 4,950,332 wherein it is proposed to substitute activated carbon with a certain macroporous copolymer adsorbent for decolorizing sugar solutions. It is said that the adsorbent employed therein can be as effective as carbon in adsorbing or removing color bodies from sugar solutions.
While the process described in U.S. Pat. No. 4,950,332 has advantages, namely the elimination of the need for activated carbon, the process also has drawbacks. For example, like processes which use activated carbon, the process requires three steps to purify a sugar solution. There is no mention in the patent of a desire to obtain a more cost-effective or efficient process for purifying sugar solutions, particularly, one that performs both decolorization and demineralization in a fewer number of steps. Thus, there is an ongoing need in the art for a more efficient, cheaper, and simpler process for purifying sugar solutions.